The degradation of trees at the edges of tropical forests is more widespread than previously thought, according to new research.
The study, published in Nature, explains that trees near deforested or degraded areas of the forest are more vulnerable to drought, as well as to human activity such as logging. These “edge effects” are measurable up to 1.5km into the forest, the authors find.
This is an “amazing result”, a study author tells Carbon Brief, because previous studies detected these effects only within the first 120 metres of the forest edge. The new figure indicates that 18% of the remaining tropical moist forests are impacted by edge effects – an area more than 200% larger than previously estimated.
Experts not involved in the study tell Carbon Brief that quantifying tropical forest degradation is “frustratingly elusive”. And while some praise the methods used in the paper, others advise caution when interpreting the conclusions.
Two Brazilian scientists also tell Carbon Brief that the study overlooks important work from institutions in the global south who are also working on this problem. They advise that scientists from local groups should be invited to contribute to research in this area.
Forest height
Tropical forests account for around 45% of forest cover globally. These forests are well-known for their high biodiversity and the crucial ecosystem services that they provide. They also hold around one-quarter of all land-based carbon.
The new study assesses how deforestation and degradation affect “moist tropical forests” – tropical forests in the equatorial belt with a fairly consistent annual temperature and high levels of rainfall. Tropical dry forests and deciduous forests are not included in the analysis.
Research shows that around 17% of tropical moist forests disappeared over 1990-2021, largely due to human activity such as logging and fires. Of the 1,071m hectares that remained globally in 2019, around 10% were degraded, the new study says. This means that they suffered human-induced “disturbances” that led to a partial loss of their tree cover or function.
Furthermore, trees at the edges of tropical forests have higher mortality rates than trees in the centre, because they are more exposed to disturbances such as fire and drought. When intact forest landscapes become fragmented – for example, due to logging, fire, drought or the construction of roads into the forest – these “edge effects” can lead to further forest degradation.
The authors use data collected by the Global Ecosystem Dynamics Investigation (GEDI) instrument on the International Space Station to assess the forest structure – such as canopy height and aboveground biomass – over the past four years.
To measure canopy height, the authors calculate the “RH98” value – the height of the top of the canopy or the nearest tallest vegetation in the area. This is an important measure of forest health and maturity. Aboveground biomass measures the aboveground woody biomass per unit area and is also a good measure of forest health.
They combine this with data from the Tropical Moist Forest dataset, which uses Landsat satellite imagery to show how tropical moist forests have changed over 1990-2022.
The plot below shows the canopy height for different types of moist tropical forests. The rows show intact forests at least 3km from a forest edge (top row), degraded forests (second row), the edges of forests (third row) and forest regrowth (bottom row), as shown in the maps below.
Darker blues indicate taller forest canopies. The map shows where the forests are located, and the bar charts on the right hand side show the overall distribution of different tree heights.
The tallest intact moist tropical forests are found in south-east Asia, where the average canopy height is 34m, the study finds. West and central Africa and Central and South America have average forest heights of 29m. This is because intact tropical forests in Asia, which are typically dominated by “hardwood wind-dispersed species”, are typically taller, the authors say.
The map also shows that degraded forests, forest edges and areas of forest growth have a greater proportion of shorter trees on average.
The forest edge
The study investigates two different types of forest edge effects, exploring how areas of deforested and degraded land impact nearby trees.
Dr Lilian Blanc is an author on the study and researcher at the French Agricultural Research Centre for International Development. He tells Carbon Brief that the effect of nearby degraded land “was not considered in previous studies”.
The graphs below show how areas of deforested land affect tree canopy height. The charts at the top show the average distribution of canopy heights of undisturbed forests in the Americas, Africa and Asia. The line colours indicate the distance of those trees from the forest edge, with yellow indicating a short distance and blue indicating a large distance.
The bottom map shows how far into the forest edge effects are present, by measuring the distance from the forest edge at which the height of the forest reaches 95% of the height of the intact, undisturbed forest.
The authors find the greatest edge effects from deforestation along the “forestation fronts of the Amazon”, in Borneo and Sumatra coasts marked by high fragmentation levels, and on the borders of the Congo basin.
They also record a decrease in canopy height up to 350, 400 and 1,500 metres from the deforested edge in the Americas, Africa and Asia, respectively.
The authors find that within 120 metres of trees that have been degraded due to logging and burning, the average canopy height in undisturbed forests is 15% and 22% lower, respectively.
The authors also investigate how quickly the forest can recover from logging and fires, concluding that while there is “fast regrowth of pioneer and understory species”, there is “no significant recovery in canopy height in the 30 years following the creation of a forest edge”.
Forest degradation can also increase the likelihood of deforestation, the authors say. They warn that forest height and distance to the edge of the forest are “strong predictors of deforestation”, as forest fragmentation makes the interior of the forest more accessible to loggers.
It adds that there has been selective logging 500 metres from the forest edge in Africa and the Americas, and even deeper in Asia.
Agriculture and road expansion trigger a 20-30% reduction in canopy height and biomass at the forest edge, with “persistent effects” measurable up to 1.5km inside the forest, the authors find. Blanc tells Carbon Brief that this is “an amazing result” as previous studies only looked for edge effects up to 120 metres from the forest edge.
The authors also calculated the edge effect using total above ground woody biomass, instead of canopy height. Using this metric, the authors conclude that the total area of forest with this edge effect is 18% of total global forest area in 2022 – an area more than 200% larger than previously estimated.
Prof Simon Lewis – a professor of global change science at University College London’s department of geography – tells Carbon Brief that this is a “striking new result”.
It implies that “the negative impacts on remaining forest from the creation of forest edges are much more extensive than has been commonly documented”. It also means that “forest protection of large blocks of forest is going to be more important than we previously thought”, he says.
Overall, the study is “an important step forward in monitoring forest disturbance, which is a very tough problem”, Lewis says. However, he adds that “care is needed” when looking at some of the observational data, saying that he “trust[s] the broad patterns of biomass loss following logging, edge creation and fires, but not the specific biomass loss values from these disturbances”.
Dr Peter Potapov – a researcher in the department of geographical sciences at the University of Maryland, whose work was cited extensively in the new study – says “the conclusion that edge effects are degrading 18% of the remaining humid tropical forest is an overstatement”.
He says that forest degradation depends on other factors, such as land-use regulations, and argues that “the assumption that all forests 1.5km away from the edges are degraded may undermine ongoing conservation efforts.
Expert response
These comments reflect the mixed response that the new study has received.
Prof Matthew Hansen – a remote sensing scientist at the University of Maryland’s department of geography – tells Carbon Brief that forest degradation is “a frustratingly elusive dynamic to quantify”. However, he praises the study for being “very clear and ambitious”.
Potapov, who has published research with Hansen, tells Carbon Brief that the results broadly confirm existing findings, but warns that there are some “major limitations” with the study.
For example, he says the method does not include a “matching technique” to separate the effect of human management on tree height from the natural factors such as elevation, soil quality and floods. He also warns that the observations “failed to correctly map anthropogenic disturbances in humid tropical forests”, adding:
“The authors greatly underestimate selective logging in Gabon, while the natural non-fire disturbances like river meandering and windfalls in South America were probably treated as human-caused degradation.”
Dr Flávia de Souza Mendes, a programme manager in forest and land use at satellite imagery firm Planet Labs, says the study is “well written”. However, she laments that “there are several local groups from the global south that have been studying this topic and are not part of this study”. She suggests that scientists carrying out similar studies should “invite more local researchers to take part”.
She also tells Carbon Brief that this paper “did not take into account studies carried out by local researchers on the relationship between degradation and deforestation”.
For example, she highlights a report by Brazilian researchers which finds that, in some regions of the Amazon, 86% of degraded areas were not subsequently cleared in the following decades. This is not in line with the findings of the new study, where degradation “has a crucial role in predicting future deforestation”, she says.
Prof Celso Silva-Junior – a research scientist in amazon ecology and remote sensing at Brazil’s Universidade Federal do Maranhão – tells Carbon Brief that the study “reproduces the findings of our research group, which has been investigating large-scale forest edge effects, using remote sensing technologies, since 2016”.
He says that the paper’s findings concerning biomass loss beyond 120 metres from the forest edge are “critical”. However, he emphasises the importance of the “local knowledge of tropical scientists” who are “deeply involved in the establishment of the conceptual framework for treating this relevant problem”.
The post Tropical forest degradation due to ‘edge effects’ is 200% higher than thought appeared first on Carbon Brief.
Tropical forest degradation due to ‘edge effects’ is 200% higher than thought
Steven Stone is acting director of the United Nations Environment Programme’s Office of Science
In 1934, American economist Simon Kuznets presented a paper to Congress advocating for a new way of measuring economic performance.
The United States was reeling from the Great Depression, and Kuznets – a future Novel prize winner – wanted to gauge just how badly the country’s economy had been dented.
His metric, which would come to be known as gross domestic product (GDP), was a breakthrough. But as pioneering as it was, Kuznets saw its limitations.
“The welfare of a nation can scarcely be inferred from a measure of national income,” he wrote in the 1934 paper.
Some nine decades on, we have largely forgotten that message. GDP has become a barometer of economic progress, a kind of one-number-that-rules-them-all upon which national policies turn and governments rise and fall.
With the climate crisis deepening by the day – as evidenced by the heatwaves and wildfires now searing Europe – our attachment to GDP is looking like a problem.
In a single-minded pursuit of GDP growth, humanity is inadvertently feeding several environmental crises that, over the long run, threaten to make most of us poorer, sicker and more miserable. Climate change alone could slice 20 per cent off global GDP by 2100 – a staggering number.
Clear-cutting boosts GDP not wealth
We need to broaden our vision and definition of economic success before it’s too late.
I grew up in the 1970s and 80s surrounded by the mixed hardwood forests of the northeastern United States. For me, the trees were a refuge, a place to run, discover and savor the history and mystery of the land and its people.
Those experiences with my friends were more important than the amount of money in my pocket. And they led to a realization early on in my career as an economist: that wealth is about more than just income.
This is one of GDP’s most significant oversights.
With every forest we clear cut and every ounce of fossil fuel we burn, GDP rises. But through those actions, we are whittling away at the natural world, which supplies us with food, water, medicine, clean air and countless other essentials.
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By focusing only on GDP, we’re ignoring what’s happening to the natural assets on which our prosperity ultimately depends. It’s like we’re driving a car and only looking at the speedometer, not the energy remaining in the battery.
That is the difference between measuring income versus measuring wealth.
The answer to this dilemma lies in looking beyond GDP. We must start considering a broader range of indicators when making policy decisions.
From an environmental perspective, that means measuring and valuing natural assets like forests, water, soil, biodiversity and clean air. By assigning a value to nature, decision-makers can better understand the economic consequences of, say, strip-mining a mountain top or letting plastic waste overwhelm a river.
There is still some debate over how exactly to do this kind of natural capital accounting. But that’s not a reason to dismiss it, as many have done. It took years of refinement to end up with the GDP formula we have today.
Costa Rica’s example
The idea of looking beyond GDP isn’t only a theoretical debate. Countries and communities around the world have started to make economic decisions based on their natural assets. A prime example is Costa Rica, a biodiversity hotspot where a years-long effort to conserve land and seascapes has led to a boom in tourism. That in part helped elevate the country into the club of high-income nations.
This kind of environmentally focused economic decision making can pay huge dividends. By stabilizing the climate, ending pollution and halting the loss of the natural world, humanity could save millions of lives a year and create US$20 trillion in economic benefits annually by 2070, found the Global Environment Outlook 7, a 2025 report from the United Nations Environment Programme (UNEP). The report was funded by the European Union among others.
I began my career as an economist before moving to UNEP, which focuses on solving the world’s thorniest environmental problems. During that time, I’ve come to appreciate that “wealth” means more than simply “income.” True prosperity means being able to provide for ourselves now and into the future. Anything short of that is an empty kind of affluence – and ultimately doomed to be short-lived.
As deadly heat blankets our cities, species slip into extinction and the planet struggles with rising toxicity and pollution, I am convinced that we can do better at measuring what matters. And that means updating and expanding how we measure economic progress.
The post As fires burn and temperatures soar, it’s time to imagine a world beyond GDP appeared first on Climate Home News.
As fires burn and temperatures soar, it’s time to imagine a world beyond GDP
Amira Odeh Quiñones is a hydrologist and Caribbean organiser for the 350.org climate campaign group
El Niño, likely to be one of the strongest in modern history, has arrived on Caribbean shores.
Drought is slowly creeping up on our islands. But unlike the fiery wildfires ravaging parts of Europe, there’s no smoke signalling the damage being done, no sirens to warn of the danger. Only announcements from public health officials to stay indoors and remain hydrated — as if outdoor workers and farming communities have the luxury to heed such advice.
During El Niño, strong atmospheric winds alter rain patterns and trap heat across the Caribbean. But while we have experienced El Niño many times before, it has become very visible in recent years how climate change is making this natural phenomenon worse.
Across the Greater Antilles, temperatures are soaring past 38°C (100°F), with real-feel indexes reaching a gruelling 43°C in parts of Puerto Rico where I live. Cuba has it worse. Widespread power outages mean that methods for cooling down are unavailable for most of the day, leaving millions of vulnerable people at risk of heat stroke when temperatures hit 38°C.
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During the last strong drought a decade ago, I had water only two days a week in my home. Today, there are many families whose taps are about to run completely dry. Water authorities have already begun strict rationing in some municipalities, with more on the list scheduled for rationing if conditions don’t change.
Water rationing is far more than an inconvenience; it is an immediate health risk. This means thousands of people need to constantly haul heavy buckets up flights of stairs just so they could bathe, cook, stay hydrated – the basics of survival.
Heat causes health problems
Puerto Rico is home to roughly 300,000 elderly residents. Many live alone, isolated and without support. They risk severe physical injury when carrying heavy water containers, and are wont to suffer from silent heat exhaustion in unventilated rooms.
Furthermore, when water shortages force residents to store water in open household containers, it inadvertently creates breeding grounds for Aedes aegypti mosquitoes. Paired with scorching temperatures that tend to shorten the mosquito breeding cycle, the region is facing explosive outbreaks of dengue fever that endanger our most vulnerable: children and the elderly.
The economic fallout is equally devastating. Dry fields mean millions of dollars in lost crops, forcing small agricultural businesses to collapse, needing urgent government relief to survive. Extreme fuel shortages have already paralyzed Cuba’s agricultural sector, cutting food output by 60% – the El Niño dry spell threatens to decimate it.
At sea, warmer ocean waters fuel massive influxes of sargassum seaweed. Rotting sargassum chokes our beaches, destroying the local tourism industry that so many working families rely on. Tangled seaweed also damages nets and boat engines, slashing fish catches and driving up equipment costs for local fishers.
In the south of Puerto Rico, the coastal town of La Parguera is currently witnessing a historic amount of sargassum on its shores. This has halted most of the boating activity in the area, which is the seaside town’s main tourist draw and economic driver.
All over the Caribbean, from town halls to local group gatherings, the story I hear is always the same: constant headaches, lost work hours, failing health, and a sense that quality of life is silently being stolen. The compounding effects of heatwaves, drought, and marine destruction are exhausting our people, our islands.
Climate change to blame
Climate change makes each El Niño year hotter and more damaging. Higher baseline global temperatures increase the energy and moisture available for extreme weather. Latest projections show that El Niño may push the monthly global average temperature past 2°C of warming for the first time in early 2027. In the Caribbean islands, that will not just be breaking records – it’ll be breaking lives.
Recently, I had the opportunity to share a panel with climate scientists behind what is known as the field of “attribution science” – or the science that compares today’s climate conditions to what the Earth’s climate would be like without human activity, particularly burning fossil fuels. They’re unequivocal: it’s no longer a question of whether extreme weather is caused by climate change, it’s just a question of how much.
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Attribution science recently got a boost from the U.S.’ top scientific advisory body. The National Academies of Sciences, Engineering and Medicine recognized that researchers’ methods have advanced considerably in recent years, resulting in better assessments on how much extreme weather can be attributed to human-caused climate change. It noted that attribution findings could be relevant in some types of legal cases, including those seeking damages from oil companies for climate impacts.
This crisis, which is already taking a heavy toll on our communities’ survival, needs real, urgent, and structural action that goes beyond aid. With similar droughts now gripping parts of Asia and Africa, we’re falling into the familiar narrative of treating the looming humanitarian crisis as if no one was to blame, as if it is being caused solely by a natural phenomenon we can’t control.
It’s not. The world was already on fire before its regular visitor, El Niño, came. While we need humanitarian action, we need climate action too, in order to permanently put out the flames.
The post When taps run dry in the Caribbean, it’s not enough to blame El Niño appeared first on Climate Home News.
When taps run dry in the Caribbean, it’s not enough to blame El Niño
China has released a five-year plan dedicated to addressing climate change.
The 15th five-year plan for a national response to climate change is the latest in a series to outline in-depth climate and energy targets for the 2026-2030 period.
These include five-year plans for “building a Beautiful China”, developing a “new-type energy system” and developing renewable energy.
There are also separate “action plans” for the 2026-2030 period, such as for peaking carbon emissions.
China has pledged to peak its emissions before 2030 and reach carbon neutrality before 2060.
The new plan does not include any major new targets, instead consolidating and reaffirming existing policies.
Nevertheless, it includes significant signals on key policy areas, such as non-carbon dioxide (CO2) greenhouse gases, global climate governance and carbon markets.
Below, Carbon Brief examines some of the notable elements in the latest five-year plan and what it reveals about China’s policy direction through to 2030.
What does the climate plan cover?
The Ministry of Ecology and Environment (MEE) released the plan in late July, in unison with 18 other government departments. These include the National Development and Reform Commission (NDRC), China’s top economic planning agency, and the National Energy Administration.
The document covers a range of topics, including CO2 emissions, other greenhouse gases (non-CO2 GHGs), carbon markets, carbon footprints, climate adaptation and international cooperation on climate change.
For the first time at the five-year plan level, the plan creates a comprehensive target system covering all areas of climate policy, say officials in a MEE Q&A.
They describe it as “the main policy instrument” for advancing China’s climate action during 2026-2030.
China rarely issues high-level multi-year policies dedicated to “responding to climate change”. In 2014, the NDRC published a plan on the topic running through to 2020, but this was not linked to a five-year plan period.
Qin Yan, principal analyst at ClearBlue Markets, tells Carbon Brief that the plan shows that China’s climate governance has reached “an unprecedented strategic level”.
She adds that the plan creates an “all-encompassing target system” to support China’s Paris Agreement climate pledges for 2030 and 2035.
In its 2030 pledge, China aimed to peak emissions “before 2030” and reduce carbon intensity – its emissions per unit of GDP – by more than 65% from 2005 levels.
Last year, president Xi Jinping personally announced China’s 2035 pledge to cut China’s greenhouse gas emissions to 7-10% below peak levels by 2035, while “striving to do better”.
The five-year plan marks a new phase in China’s climate policy, according to researchers at CIB Research, an economic research body affiliated with the Industrial Bank, whose largest shareholder is the Fujian provincial government.
Their analysis adds that the plan represents a broad effort to strengthen China’s climate-governance system, implementation mechanisms and underlying capacity.
Nevertheless, several headline targets and policies in the document simply reiterate already established plans.
These include:
- Cutting carbon intensity by 17% across the five years
- Reducing carbon intensity per product in industries under China’s carbon market by 3%
- Substituting fossil fuels with renewables
- Strengthening climate adaptation
- Supporting the “free flow” of cleantech
What does the plan say about non-CO2 GHGs?
The plan also goes into detail on China’s approach to non-CO2 GHGs. This includes reaffirming a target of an emissions “reduction capacity” from these gases totalling 30m tonnes of CO2 equivalent (MtCO2e) by 2030, although the baseline is unclear.
The target previously appeared in the overarching five-year plan, as well as the plan for building a “Beautiful China”.
The goal refers to emissions reductions, which can be realised through implementing current non-CO2 emissions reduction policies and projects, says Chen Meian, programme director and senior analyst at the Institute for Global Decarbonization Progress (iGDP).
She adds that it is “relatively achievable”, with sources including increasing the number of coal-mine methane utilisation projects.
She points to an MEE explanatory note for a draft methodology under the China Certified Emission Reduction (CCER) scheme, China’s voluntary carbon-credit market. Chen says the note suggests that projects using ventilation air methane and coal-mine methane with concentrations below 8% alone could deliver around 20MtCO2e of reduction by 2030.
The note states that, currently, such projects are estimated to be able to “generate annual emission reductions of approximately 4.5MtCO2e”.
In addition, Chen says, measures targeting industrial nitrous oxide (N2O) and hydrofluorocarbons (HFCs) could help make up the remainder needed to meet the target.
According to iGDP analysis of biennial reports submitted by China to the UNFCCC, China emitted around 14,000MtCO2e of GHGs in 2021, excluding land use, land-use change and forestry (LULUCF).
Non-CO2 GHGs accounted for around 2,700MtCO2e, or 19%, of the total, the majority of which was methane, as shown in the figure below.
China’s plans to curb these super-pollutants in the five-year period include coal-mine methane utilisation projects, end-of-pipe destruction technologies for HFCs and guidance on the use of catalysts to reduce N2O emissions.
The plan also calls for the recovery and replacement of sulphur hexafluoride (SF6) in power equipment.
For Chen, the plan’s focus on SF6 control is particularly noteworthy. She says the gas is “finally receiving policy attention” and that proactive action is “timely and will help avoid future emissions growth” as China’s power system expands.
What does the plan say about global climate governance?
One of the plan’s clearest objectives for international cooperation is for China to play a more active role in global climate governance.
By 2030, it says China should markedly increase its “influence, guiding power, shaping power and moral appeal” in this area.
It says China’s climate action could also feed into the Global Governance Initiative, a policy initiative aimed at reforming the global governance system.
China will also aim to “build a new narrative on climate governance”, it adds.
Prof Thomas Hale, a professor in public policy at the University of Oxford’s Blavatnik School of Government, writes on LinkedIn that the plan “marks a major rhetorical shift” towards China being increasingly willing to “lead and shape” global climate action.
Another clear focal point for international cooperation is in carbon markets.
The plan calls for China to expand the global influence of its carbon market, such as through international rule-setting, cooperation on standards and by hosting the China Carbon Market Conference.
Qin says China’s more active role in global carbon pricing is already evident in the launch of the open coalition on compliance carbon markets with the EU and Brazil. This coalition is expected to adopt a work plan at the China Carbon Market Conference in September.
Qin also notes that China “could become the world’s largest [carbon] offset buyer” as its energy transition progresses.
The country would, therefore, “benefit from helping shape global rules under the Article 6 framework [for carbon trading under the Paris Agreement]”, she adds.
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The post Q&A: What is in China’s new five-year plan for climate change? appeared first on Carbon Brief.
Q&A: What is in China’s new five-year plan for climate change?
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